Paper and method of making the same.



EDWARD F. MILLARD, 0F WATEB'I'OWN, MASSACHUSETTS.

PAPER AND METHOD OF MAKING THE SAME.

No Drawing.

To all whom it may concern:

Be it known that I, EDWARD F. Mmm'nn, a citizen of the United States, residing at Watertown, in the county of Middlesex and State of Massachusetts, have invented certain new and useful Improvements in Paper and Methods of Making the Same; and I do hereby declare the following to be a full, clear, and exact description of the same.

This invention relates to the manufacture of paper; the primary, object in view is the production of a novel paper which is composed wholly of raw wood pulp stock 111 a proper mixture of both short thin and relatively long fibrous material, without any chemical treatment or its equivalent as a step in the manufacture.

According to previous methods of commerciallymanufacturing paper from wood pulp, it has been found invariably necessary to chemically treat at least a portion ofthe wood or pulp, in order to produce a pulp suitable for making paper. The most usual procedure prior to my invention is to use a proportion of plain ground wood pulp and to mix therewith a proportion Varying from twenty-five to forty-five per cent. of chemically made pulp, 2'. 6., in order to provide a proper mixture for manufacture into a commercial paper product. It is most desirable to use a relatively large proportion of plain ground wood pulp, because of its cheapness and the relatively large output from a given quantity of raw wood, but the fact that this pulp as ordinarily ground does not have the necessary string texture to it, makes the admixture of a proportion of chemically made or sulfite-pulp necessary to efiect matting and to give strength to the paper product. These two pulps were combined in beaters and subsequently run through the paper makingmachine. It has always been difiicult, however, to thoroughly mix a sulfitepulp with a ground wood pulp, and the cost of a chemically prepared pulp is so great that as large a proportion of plainground wood pulp as could be used in the resulting mixture was generally employed, often to the detriment of the resulting paper product.

In order to simplify the pulp' making process, and to eliminate the expensive pro portion of sulfite-mixture heretofore necessary in the commercial manufacture of newspaper stock or the like, it has been suggested to treat the wooden block sv before being ground, subjecting them to chemical action,

Specification of Letters Patent.

Patented Oct. 23, 1917.

Application filed June7, 1916. Serial No. 102,822. Y

or by a step requiring heating or cooking,

to so prepare the wood that it could be ground so as to produce a pulp with a suflicient fiber to give strength, and mix with the fine ground or sawdust produced from the untreated or uncooked wood. Theseprior attempts, however, have been entirely ing, I have made several inventions which enabled me to produce a ground all raw wood pulp with fibers of substantially uniform length. My inventions in this line are illustrated in certain of my prior Patents Nos. 149,586, March 31, 1891; Reissue 11,590, March 2, 1897; and 780,213, January 17, 1905. While by the novel system of grinding which I have discovered, a pulp was produced with suflicient fiber to enable stock to be made, providing a substantially uniform composition capable of giving great strength to a product suitable for newspaper work or the like, yet this product was not satisfactory because a suitable surface and finish was not provided. It is, of course, possible to make a commercial paper entirely from sulfite-pulp, or from the uniform fibered pulp produced in accordance with the disclosure of my patents above mentioned, but the product resulting therefrom is not as suitable for the uses of the trade, not having the surface and finish which is imparted to paper made from a pulp having a mixed texture. My present mvent on consists in the discovery that a pulp having a mixed fibrous composition, produced entirely without chemical action, and wholly by grinding from raw wood can be manufactured preferably by using a machine similar ner, but by a different adjustment of the Y machine or another machine; This produces a pulp composition of a mixed fibrous nature. Thus I am enabled to secure the ada vantages of ground wood pulp, producing a very cheap stock, there being a larger proportion of pulp from a given supply of wood than When a proportion of chemically made pulp is included, entirely eliminating the step of the chemical treatment, and, in .fact, producing a paper with a better finish and surface, more suitable to receive printing, etc., than where a sulfite-mixture is used. Sulfite-pulp alone does not afiord a suitable surface for printing, While the usual mixture of ground wood pulp with twentyfive to forty-five per cent. of sulfite-pulp does not produce paper of uniform strength, because the sulfite and ordinary ground wood pulp cannot be thoroughly mixed.

Tn carrying out my present process, ll find it advantageous, in fact, essential, to use a grinding machine, as illustrated in my prior Patent 780,213, in order to provide the short thin fiber as one step in my present process of manufacturing paper-pulp. I prefer to employ a three-pocket grinder and have the same set to produce fibrous pulp of suitable length to afiord short thin fibers in the pulp product. Tn making the longer fibered pulp as another step in the present process, I may also employ a similar grinder, set to produce a long fibrous pulp. The long fibered pulp is required to loosen up or free the short fibers and give running qualities to the mixture in the manufacture of the paper, permitting carrying ofi of the water with sufficient rapidity for commercial handling and the short fibered pulp imparts the necessary strength and finish to the resulting product. I may thus utilize two machines, one producing short thin fibered pulp, and the other a relatively long fibered pulp, and mix these two products preferably in a substantially equal proportion, thereby producing an allground wood pulp of a mixed fibrous composition, entirely without the aid of chemicals, solutions, cooking, or by sulfiteadmixture of any kind. The paper made from such mixed all-fibrous stock ground directly from raw wood is of very even texture and of smooth surface, finish, and with snap and handling or klang approximately equal to that of rag made paper. The result obtained, 'Z. 6., paper made by my present process and from all-ground wood pulp, is remarkable, in that it approaches and nearly equals the paper made from rag pulp, heretofore the finest and most expensive stock for newspapersand T attribute thisv largely to the fact that my process permits a better texture because both the long fibers and the short fibers retain their fiber form,

because the entire ground raw wood composition supplies a better finish and surface than the' usual sulfite and ground wood plup, and because the short and long fibers mat, combine and interlace in a peculiarly firm, smooth manner.

The paper product which is produced from the paper pulp made by my present process, when run through an ordinary paper making machine, is notably superior to the sulfite mixture, being of uniform strength, surface and finish, entirely without weak spots, or streaks, so common to sulfite made pulp. These weak spots and streaks often result from the water not running out of the pulp, the fine sawdust or flour pulp filling up the felt carriers and the difliculty of properly mixing sulfite-pulp with ground pulp. Each of these difficulties is entirely eliminated by my process, the resulting paper produced is of better finish, especially with a surface suitable to receive type and not fill up the type, blur, or run the printing when being run at high speed through a printing press. Also being of uniform strength and texture, no difficulty is experienced in running such stock through the paper making machines. While I have explained that it is preferable to use both the short thin fibrous pulp and the long fibered pulp in substantially equal quantities, it will be readily understood that these proportions may be varied in a considerable degree for making difierent grades of paper. It will be noticed that the product made by my process constitutes a paper, especially suitable for newspapers and therefore with a good print-receiving mitted by a paper making machine in a given length of time, as the delays, stoppages, due' to breakage, etc., formerly customary, are eliminated, my product being run smoothly and even more rapidly through a paper making machine than has formerly been possible.

What is claimed is:-

1. The improvement in the art of paper making which consists in preparing mechanically directly from raw wood a pulp stock composed substantially of short thin raw wood fibers, separately preparing mechanically directly from raw wood another pulp stock composed substantially of relatively longer raw wood fibers, mixing the longer fibrous stock with the short fibrous stock in substantially equal proportions to form a pulp mixture having a suficient quantity of long fibers to loosen up the short fibers and to facilitate running of the pulp combined with a suificient quantity of short fibers to impart strength and finish to the paper, and preparing the paper directly from, such pulp mixture.

2. The method of making paper pulp 1m wholly from ground raw wood which consists in specially grinding a proportion of raw wood to form a pulp stock composed substantially uniformly of short thin raw wood fibers, separately grinding another proportion of raw wood to form a pulp stock composed substantially uniformly of relatively longer raw wood fibers, and mixing the longer fibrous raw wood stock with the short fibrous raw wood stock in substantially equal proportions to form a pulp mixture for paper making having a sufl'icient quantity of the longer fibers to loosen up the short fibers and to facilitate running of the pulp combined with a sufiicient quantity of the short fibers to impart strength and finish to the paper.

3. As a new and improved article of man ufacture, a pulp for paper making formed wholly of two separately ground raw wood stocks, one stock being of short fibrous nature and the other of relatively longer fibrous nature, mixed together in substantially equal proportions to form a piggmixture for paper making having a cient quantity of the longer fibers to loosen up the short fibers and to facilitate running of the pulp combined with "a suflicient quantity of short fibers to impart strengthand finish to the paper.

4. As a new and improved article of manufacture, a paper made wholly of ground raw wood composed of two separately ground raw wood pulp stocks, one stock being of short fibrous nature and the other of longer fibrous nature, mixed together in substantially equal. proportions to form a pulp mixture from which the aper is made,

having a suificient quantity 0 long fibers to loosen up the short fibers and to facilitate running of the pulp during the manufacture of the paper, combined with a sufiicient quantity of short fibers to impart strength and finish to the paper. 

